Meta AR/VR Patent Shares Reflective Polarizer Coated Fresnel Lens

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(XR Navigation Network 2023年12月26日）XR头显用户可能不会对菲涅耳透镜感到陌生。对于这种常见的元件，厂商一直在尝试各种优化方案，从而帮助减轻整体系统的重量和尺寸。在名为“Reflective polarizer coated fresnel lens”的专利申请中，MetaA reflective polarizer-coated Fresnel lens is then presented.

The invention describes devices that may include an optical structure including a Fresnel lens assembly. Exemplary Fresnel lens assemblies may include a reflective polarizer configured, for example, to reflect a first polarization of light and transmit a second polarization of light. The reflective polarizer may reflect one rotation of the circularly polarized light and transmit another rotation of the circularly polarized light. Exemplary devices may include a beam splitting lens, or may include a second Fresnel lens assembly. The beam splitting lens may include a beam splitter formed as a coating over the lens.

By reducing the losses associated with the beam splitter (replacing the beam splitter with a polarized reflector), the use of a Fresnel lens assembly can increase the optical efficiency of the optical configuration, and increased optical efficiency can result in an improved image, increased lens efficiency, reduced power consumption, and/or reduced heat generation for a given brightness.

The wavelength-dependent properties of the Fresnel lens assembly or polarizing reflector may be adjusted by adjusting one or more parameters of the multilayer membrane structure. In one embodiment, the reflective polarizer may have a specific operating bandwidth and said operating bandwidth may be adjusted using one or more parameters of the one or more components.

FIG. 2A illustrates a Fresnel lens assembly 200 including a Fresnel lens 210 and a reflective polarizer 220. in this example, the surface of the Fresnel lens 210 is coated with the reflective polarizer 220. the Fresnel lens assembly may be used as a reflective polarized Fresnel lens.

FIG. 2B illustrates a cross-sectional view of a Fresnel lens assembly 200 including a Fresnel lens 210. The faces of the Fresnel lens 210 support layers that form a reflection polarizer 220. In this example, the multiple faces of the Fresnel lens are planarized using a filler layer 230. Said filler layer may include an optically transparent material, such as glass or an optical polymer. Said filler layer may include air, liquid, polymer, glass, ceramic, or a combination thereof.

FIG. 2C illustrates an optical assembly 270 comprising a Fresnel lens assembly 200 disposed at least partially between a first substrate and a second substrate. a first substrate 272 may support the Fresnel lens assembly. The second substrate 274 may provide mechanical protection for an upper surface profile of the Fresnel lens assembly.

The gap 276 between said contoured substrate and said second substrate may comprise said filler layer. Said filler layer may include a gas, a liquid, or a solid. In one embodiment, the solid filler layer may provide a second backing so that a separate second backing is omitted.

In one embodiment, the second substrate or the first substrate may include a reflection polarizer. The multi-faceted surface of the Fresnel lens may be planarized using a filler layer and the reflection polarizer may be disposed above said filler layer.

At least one of the Fresnel lens and the filler layer may have a low birefringence value and may have an optical delay of at least one visible wavelength.

FIG. 3 illustrates light propagation through a cross-section of an example Fresnel lens assembly 300. The Fresnel lens assembly 300 includes a Fresnel lens 310, a reflective polarizer 315, and a filler layer 320.A face 312 of the Fresnel lens 310 supports the reflective polarizer 315.Said reflective polarizer is configured to reflect a first polarization of light and transmit a second polarization of light. The light beam 305 may include light with a first polarization that is reflected by the reflection polarizer 315 to form a reflected light beam 328 and may include light with a second polarization that is transmitted by the reflection polarizer to form a transmitted light beam 325.

FIG. 4 illustrates a cross-section of an example Fresnel lens assembly 400, said assembly comprising a Fresnel lens 410, reflective polarizers 415, 416, 417, a filler layer 420, and an absorptive polarizer 425.Incident light is shown as a ray beam 405, and reflected light is shown as a ray beam 428.Said absorptive polarizer 425 transmits the light reflected by the reflective polarizers 415, 416, and 417 of a first polarization. The absorbing polarizer may absorb a second polarizer of light. An order 418 may be disposed between adjacent reflective polarizing surfaces.

In one embodiment, a reflective layer may be used in place of a reflective polarizer. Stray light rays (e.g., rays 430 and 435) may be transmitted through the Fresnel lens assembly. The stray rays may pass through a gap between the reflection polarizers, such as through a gap between reflection polarizers 416 and 417. Stray light may be generated due to multiple reflections from the reflection polarizers and/or other interfaces.

FIG. 5 illustrates a cross-section of an exemplary Fresnel lens assembly 500 and includes a Fresnel lens 510, a reflective polarizer 515 disposed on one face of the Fresnel lens 510, a filler layer 520, an absorptive polarizer 525, and a second absorptive polarizer 540. an order 518 may be disposed between adjacent facets. The incident light is shown as a ray beam 505 and the reflected light is shown as a ray beam 528. the Fresnel lens assembly 500 may function in a manner similar to the Fresnel lens assembly 400 described above in connection with FIG. 4. A second absorbing polarizer 540 may absorb stray light such as rays 530 and 535.

FIG. 6 illustrates a cross-section of an example Fresnel lens assembly 600 and includes a Fresnel lens 610, a reflective polarizer 615 disposed on one face of the Fresnel lens 610, a filler layer 620, a first polarizer 625, and a second polarizer 640.In this example, a ray beam 605 may be polarized by the first polarizer 625. The ray beam 605 may have a polarization state that is preferentially transmitted by the reflection polarizer 615. The second polarizer 640 may be configured to preferentially transmit the ray beam 605 to form a ray beam 645.

FIG. 7A illustrates a manufacturing apparatus 700 including a Fresnel lens 705 having facets 708. a reflection polarizer 720 is supported by an elastomeric element 710. The reflection polarizer is divided into portions corresponding in size to the facets 708. The elastomeric element 710 is supported by a substrate 740, which may include a rigid element such as a plate.

The elastomeric element 710 may be pushed against the Fresnel lens 705, allowing portions of the reflection polarizer 720 to adhere to the Fresnel lens 705 above a corresponding face 708 of the Fresnel lens 705. The substrate 740 may be coupled to or otherwise in mechanical communication with at least one actuator configured to cause the elastomeric element to impinge on one or more faces of the Fresnel lens upon receipt of an appropriate control signal from the controller.

Simulation results show that the reflective polarizer can be adhered on top of the 708 surface without generating excessive stress in the reflective polarizer. The stress can be adjusted by adjusting one or more parameters, such as the stiffness of the substrate, the stiffness of the elastomer, the rate of deposition, the provision of a compressible adhesive layer, and the like.

FIG. 7B shows a portion of the fabrication apparatus 700. Initially, the stress in the reflection polarizer may be approximately zero because the reflection polarizer is supported by the surface of the elastomeric element 710.

FIG. 7C shows a portion of the reflective polarizer 720 pushing against the face 708 of the Fresnel lens 705 by a force applied to the elastomeric element 710.There is some stress in the region 722 of the reflective polarizer 720 in which the reflective polarizer is being effectively transferred from the elastomeric element 710 to the face 708 of the Fresnel lens 705.The stress may not be sufficient to cause any damage to the reflective polarizer, however. any damage to the polarizer.

FIG. 7D shows the reflection polarizer 720 fully attached to one face of the Fresnel lens 705 when the elastomer element 710 is moved upwardly from FIG. 7C. At this stage of formation, the stress in the reflection polarizer is very low. The elastomer element 710 may have a surface coating that facilitates release of the reflection polarizer from the elastomer element 710. Said surface may have a surface coating that facilitates adhesion of the reflection polarizer to the face of the Fresnel lens 705.

FIG. 9 illustrates a Fresnel lens 900 including facets and steps. in this example, the Fresnel lens typically has linear facets. Said facets may include circular facets or other facet shapes, such as elliptical, oval, circular, linear, etc.

The Fresnel lens assembly 1000 shown in FIG. 10 includes a Fresnel lens 1010, a filler layer 1020 that planarizes an upper surface of the Fresnel lens assembly 1000, and reflective polarizer portions 1040 and 1050 provided on the surface of the Fresnel lens 1010.

In this example, the reflection polarizer portion may typically be rectangular. However, the size of the reflection polarizer portion covering the corresponding face of the Fresnel lens may be any suitable shape. The step 1060 may be located between adjacent reflection polarizer portions 1040 and 1050, and the step may not support the reflection polarizer portion.

In one embodiment, a Fresnel lens assembly may include a Fresnel lens, and a reflection polarizer disposed on a non-multifaceted surface. A filler layer may be used to smooth, i.e., planarize, said multi-faceted surface, and the reflection polarizer may be disposed on top of said filler layer.

Example Fresnel lenses may also include a peripheral edge, but for lens applications, the edge is not used as a light-receiving surface and may be coated with a light-absorbing coating.

In one embodiment, the Fresnel lens assembly may include a waveguide, the waveguide having at least a portion of a surface including a cutout and a step, and the at least one waveguide edge may be used as a light receiving or light emitting surface.

The Fresnel lens assembly may include a Fresnel lens having a planar surface and an opposing surface including a cut surface and a step. In one example, the Fresnel lens may include a curved surface without a cut surface, such as a convex or concave surface. The Fresnel lens may include a curved surface having a tangent surface and a step. For a given lens thickness, said steps may allow for a decrease in lens thickness and/or an increase in lens transmittance.

FIG. 11 illustrates a Fresnel lens 1100 having a lens body 1105 having a flat surface 1130 and a curved surface 1140 including facets and steps. steps may be disposed between adjacent facets.

The shot polarizer may be applied to one or more faces. The Fresnel lens 1100 may be circular and may have a central region comprising a circular central face 1150, wherein said central region comprises a peripheral region 1160 surrounding a concentric annular face.

The Fresnel lens assembly may include a Fresnel lens and a reflective polarizer, the reflective polarizer covering a tangent surface and a step of the Fresnel lens. In one embodiment, the reflection polarizer may have a first surface and a second surface conforming to the tangent and step of the Fresnel lens, and the second surface may be a plane or a sphere, for example.

The second surface of the reflective polarizer may support another layer, such as an anti-reflective layer or an anti-scratch layer, or may be an outer surface of the assembly. The surface of the Fresnel lens and/or the reflection polarizer may include a diffractor Bragg grating or a surface relief grating or other optical element.

The Fresnel lens assembly 1200 illustrated in FIG. 12 includes a Fresnel lens 1205. a reflective polarizer 1220 may be disposed on and conform to various sides of the surface 1210. A filled polymer layer 1240 may be disposed over the reflective polarizer.

FIG. 14 illustrates another example Fresnel lens assembly 1400, which includes a Fresnel lens 1410 having a flat surface 1415 and a multi-faceted surface 1420. said multi-faceted surface 1420 supports a reflective polarizer 1430. in one example, the reflective polarizer may be disposed only on the face 1424, and not on top of the step 1422.

The filler polymer layer 1440 may conform to said multi-faceted surface 1420, and said deposited reflective polarizer 1430, and may be formed with an outer surface 1450. said outer surface 1450 may include steps such as steps 1442 and facets 1444. In this embodiment, the filler polymer layer has a lens configured as a concave lens with an outer multi-faceted surface, for example including a concave surface such as a center concave surface 1446.

The Fresnel lens assembly 1400 may be configured in other arrangements. In one example, the Fresnel lens assembly 1400 may include a Fresnel lens 1410 that includes a first polymer, and a second Fresnel lens that may include a second polymer.

The optical properties of the first and second polymers may be configured to reduce chromatic aberration of the Fresnel lenses, for example, by having different optical dispersion. An example reflective polarizer may include a layer formed on a multi-faceted interface between two Fresnel lenses, or on any other multi-faceted surface of one or both Fresnel lenses. For example, the one or two Fresnel lenses may support the reflection polarizer using any suitable method, and then the two lenses may be bonded together so that the radio polarizer is located at the interface between the two lenses.

名为“Reflective polarizer coated fresnel lens”的Meta专利申请最初在2022年5月提交，并在日前由美国专利商标局公布。

Generally speaking, after a U.S. patent application is examined, it will be automatically published 18 months from the filing date or priority date, or it will be published within 18 months from the filing date at the request of the applicant. Note that publication of a patent application does not mean that the patent is approved. After a patent application is filed, the USPTO requires actual review, which can take anywhere from 1 to 3 years.